DIFFERENCE ALLOWABLE STRESS BETWEEN PVELITE AND B31.3 3

[mectub]

Hi everyone!, i'm using ASTM A516 Gr.70 (under plates and sheets table A-1 B31.3) S=23.3 ksi, to design a vessel, when i check values of allowable stress in PVElite (A516 Gr.70 formlate) , i found 20 ksi @ 100F, could you help me to understand why is that,please..

Besides PVElite list another A516 Gr.70 and under composition indicate C pipe and under form B31.3 Pp. This one has S=23.3 ksi @100F.

 

[gr2vessels]

PV Elite is a pressure vessel design software based on BPVC ASME Section VIII code. The ASME VIII lists in Section II, Table D the materials which can be used in conjunction with the Section VIII design requirements. These materials are ASME approved for use in pressure vessel design, like ASME SA-516 Gr. 70, unlike the ASTM specified materials like ASTM A-516 Gr 70 you have mentioned. Even in case of identical content in specification between ASME and the equivalent ASTM specification, you can only use the allowable stresses listed in Section II, Table D. Note that the stresse listed in ASME B31.3 are for pressure piping applications using ASTM specified materials, which might be different from ASME listed materials.
Cheers,
gr2vessels

 

[mectub]

Right! i just figured out, and get to Section II, Part D, Table A1, these and others applay for Div 1, now im going to check out table 5A to see Alloweble Stress aplicable to Div 2

 

[rsaeed]

Thanks gr2vessels for your valuable replies and comments. So may I know what each of three sources say about the allowale stress for ASTM A-516 Gr. 70
ASME B31.3 says S=23.3 ksi (as mentioned above)
ASME SEC VIII DIV 1 S= ???ksi (Please tell what it say, as I've serched and failed to find out in this code)
ASTM SECTION II TABLE D S=???ksi

Also do you mean that ASTM A-516 Gr 70 is not equivalent to ASTM SA-516 Gr 70 and what does this additional S means.

Please dont mind if my questions are silly! as I just started reading BPVC whereas I dont have ASTM SECTION II TABLE D code.

I am gratefull if you can clarify this to me.

 

[gr2vessels]

rsaeed,
Please read a bit more careful my reply, perhaps I have messed it up with to many references. Again:
1. General statement:
The ASME code for pressure vessel design specifies the ASME materials and provides the allowable stresses for these materials. It does not provide allowable stresses for ASTM materials, with only some exceptions, not relevant to your post.
2. General statement:
The ASTM materials (not ASME materials!) are only tolerated in special cases in the ASME code for pressure vessels. The ASTM A-516 Gr 70 material is not tolerated in ASME code and you shall use the allowable stresses nominated in ASME Section II, Table D for the ASME SA-516 gr 70. Please note the difference between ASTM A-516 Gr 70 and ASME SA-516 Gr 70.
3. The additional 'S' in the ASME specification is a differentiating prefix to prevent mixing with ASTM materials.
4. The allowable stress for ASME SA-516 Gr 70 is 20ksi at 100F and remains the same up to 500F.
5. Do not use other allowable stresses for the pressure vessel design, just ignore other specifications. You will understand why, later when you finished learning the ASME code.
Cheers,
gr2vessels

 

[mectub]

The three give a value for this material, thanks to gr2vessels i solved my doubts, if you are going to design a piping system under B31.3 tablae A-1, pag 144, S will be 23.3 ksi, in other hand for pressure vessels Div 1, Section II, Part D, Table 1A,Pag 18 to 20,line 22, S= 20 ksi those tables are for Div 1. In case of Div 2 Table 2A pag 280 to 282, line 36, S=23.3 ksi.

SA-XXX refers to a material approved for ASME to be used with their codes they are based on ASTM materials, besides could present some difference or not from the ASTM base material. Only when ASME approve it, gets the "S". To veify check chemical composition.

Cheers,
Mectub